1. Field
At least one example embodiment relates to an automatic carrier transfer and/or a method of automatically transferring a substrate carrier using the same, and more particularly, to an automatic carrier transfer for transferring a substrate carrier in a semiconductor manufacturing post-process and/or a method of transferring the substrate carrier using the same in the semiconductor manufacturing post-process.
2. Description of the Related Art
In general, the semiconductor industry requires high integration technology for forming more integrated circuit devices on a limited unit area and mass productivity for manufacturing a much greater number of the semiconductor devices at a time with high processing speed.
Thus, various high speed and accurate processing apparatuses may be provided in a manufacturing line for the semiconductor devices. The processing apparatuses may be arranged according to stream efficiency and the relations between the unit processes in the manufacturing line.
A wafer carrier is usually used for carrying wafers between processing apparatuses of consecutive unit processes. When a specific unit process is completed on the wafers, the completed wafers are loaded in the wafer carrier and then transferred by the wafer carrier with high speed and sufficient cleanliness to the neighboring processing apparatus for the next process.
In general, the semiconductor device is fabricated through a pre-process in which microelectronic circuits are patterned on a semiconductor substrate, such as a wafer, and a post-process in which the microelectronic circuits are cut into memory chips and each memory chip is packaged together with wirings.
The pre-process may include various pre-unit processes for forming the memory cells on the wafer, such as an oxidation process, a coating process, a developing process, an etching process, an ion implanting process, a deposition process, a metal wiring process, etc. The post-process may include various post-unit processes for packaging the memory chips or dies, such as an electronic die sort (EDS) test, a sawing process, a die attach process, a wire bonding process, a molding process, a final test, etc.
In the pre-process, the wafer sequentially moves through the processing apparatuses of the pre-unit processes step by step and the integrated circuit devices are formed on the wafer. Thereafter, the wafer experiences the post-process in which the wafer including the integrated circuit devices is cut into a plurality of memory chips, and a printed circuit board having at least one memory chip sequentially moves through the processing apparatuses of the post-unit processes step by step, to thereby manufacture the semiconductor device.
Particularly, since the pre-processes require a high degree of cleanliness, the processed wafer in the pre-process is usually loaded in the substrate carrier having a sealing front door, which is generally called as a FOUP (front opening unified pod), and then a carrier transfer transfers the substrate carrier to the next unit process apparatus for performing the next process. Since the inside of the FOUP is sufficiently sealed from surroundings by the sealing front door, the processed wafer is prevented from being contaminated in carrying the wafer between unit steps. In addition, since the processed wafer is enclosed by the front door, the wafer is prevented from being unloaded from the FOUP in carrying the wafer.
Each pre-unit process apparatus usually includes a FOUP port on which the FOUP is accurately located at a predetermined position, and a door open unit for accurately detecting the position of the FOUP and the front door and automatically opening the front door. Thus, the carrying of the wafer between the neighboring pre-unit processes is easily automated to thereby complete an unmanned process flow line in the pre-process.
In contrast with the pre-process, the post-process does not necessarily require the same degree of the cleanliness as the pre-process, and the post-unit process apparatuses do not include a component or a unit corresponding to the door open unit. For those reasons, the substrate carrier for carrying a substrate, such as a PCB, between neighboring the post-unit processes does not include a sealing door corresponding to the front door of the FOUP.
Therefore, if the substrate carrier is automatically transferred between the neighboring post-unit processes, the substrate in the substrate carrier tends to be separated from the carrier in carrying the substrate. Thus, the substrate carrier in the post-process is usually manually transferred by a worker on the manufacturing line.
Thus, the overall process time for the post-process is increased by the transfer time for the manned transfer of the substrate carrier between the post-unit processes, and as a result, an overall efficiency of the post-process is significantly reduced by the manned transfer of the substrate carrier. In addition, the manned transfer of the substrate carrier limits the number of the substrates that are loaded in the substrate carrier because the carrier transfer is performed using manpower, not using mechanical power, which also reduces the overall efficiency of the post-process. Particularly, the substrate carrier in the post-process usually includes a relatively heavy substrate such as the PCB compared with a relatively light substrate such as a wafer in the pre-process, and thus, the manned transfer of the substrate carrier has much more serious effect on the overall efficiency of the post-process.
Accordingly, there has been a need for an improved transfer system for transferring the substrate carrier in the post-process without any damage to the substrate or unexpected unloading of the substrate from the carrier.